Listing titles in English only — invisible to Japanese search queries
Amazon.co.jp's A9 algorithm ranks listings based on keyword relevance to buyer search queries. Japanese buyers search in Japanese — kanji, hiragana, katakana, and Japanese product terminology. An English-only title on Amazon.co.jp is not matching the search queries the vast majority of Japanese buyers on the platform type. It is not a language preference issue — it is a keyword absence issue. The listing simply does not appear for the searches that matter on Amazon.co.jp.